Fabrication And Properties Of Microcapsule/epoxy Resin Insulating Thermal Conductive Composites

As the development of microelectronic industries,the accuracy and lifetime of the devices are greatly influenced by the thermal conductivity problem which is caused by the high integration,high power and micromation.Thus the shrink of electronic component is limited and the developments of microelectronic industries are restricted.People know much about the thermal conductivity and insulation filler,including the types,particle sizes,shapes,types of matrix and the dispersion of matrix and filler,but combination of convective thermal conductivity and solid thermal conductivity mechanisms are rarely reported.The synthesized technology of paraffin microcapsule was researched in this article and the paraffin microcapsules with excellent properties were synthesized.The single filler and mixed filler thermal-conductivity-insulation materials are prepared with the matrix of epoxy resin,the filler of paraffin microcapsule and paraffin microcapsule/nano Al₂O₃ compound.The thermal conductivity property,insulation property,dielectric property,mechanical property and microstructure are characterized by thermal conductivity tester,digital electric bridge,universal testing machine and SEM.1.The paraffin microcapsules synthesized in the condition of emulgator PVA-1788（3wt%to the core materials）,rotating speed 1200 r/min,pH2-3 and capsule acid time 2-3 h showed the best performance.The paraffin microcapsules showed well thermo stability and high productivity,origin weight loss temperature emerged at 240^oC,covering rate reached 88.9%.The microcapsules showed spherical shape and the sizes varied from 10 to 50μm,the surface was smooth and tight,also,the density was about 0.9 g/cm³ and the filling degree was high observed by TEM.2.The paraffin microcapsule/epoxy resin thermal-conductivity-insulation materials were synthesized.The thermal conductivity property of the composite was enhanced with the increase of microcapsule component.But the new boundary thermal resistance,weak thermal convection intensity in room temperature and the lack of forming thermal conductivity network chain greatly limited the enhancement of thermal conductivity.The introduction of microcapsules decreased the dielectricconstant,also,the dielectric loss maintained at a low level.Though the conductivity of the composites increased for an order of magnitudes as the interaction of small molecule,it could still act as an excellent insulation material.The touchness and strength of the materials were increased by the introduction of microcapsule.3.As the thermal conductivity network chains were not well formed when the single filler reached the limit,paraffin microcapsule/nano-Al₂O₃/epoxy resin thermal-conductivity-insulation composites were synthesized by the introduction of nano-Al₂O₃.The thermal conductivity property was greatly increased compared with single filler in the same amount of microcapsule,which indicated that the contribution of convection thermal conductivity in the composite system could be increased by reducing boundary thermal resistant and forming better thermal conductivity network chain.